81897550020 has 576 divisors, whose sum is σ = 303459706368. Its totient is φ = 17611776000.

The previous prime is 81897549971. The next prime is 81897550051. The reversal of 81897550020 is 2005579818.

It is a happy number.

81897550020 is a `hidden beast` number, since 8 + 1 + 8 + 97 + 550 + 0 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 74928594 + ... + 74929686.

It is an arithmetic number, because the mean of its divisors is an integer number (526839768).

Almost surely, 2^81897550020 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81897550020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (151729853184).

81897550020 is an abundant number, since it is smaller than the sum of its proper divisors (221562156348).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81897550020 is a wasteful number, since it uses less digits than its factorization.

81897550020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1244 (or 1239 counting only the distinct ones).

The product of its (nonzero) digits is 201600, while the sum is 45.

The spelling of 81897550020 in words is "eighty-one billion, eight hundred ninety-seven million, five hundred fifty thousand, twenty".